Exploring Maximality Criteria of Cardiopulmonary Exercise Testing in Healthy Subjects and Patients with Chronic Respiratory Disease: A Practical Clinical Framework.

Abstract

Background: Incremental cardiopulmonary exercise testing (CPET) is used to assess exercise capacity and identify mechanisms of exercise limitation. Identification of test maximality is essential for correct interpretation, yet no consensus exists on the defining criteria. This study evaluated the performance of different V˙O2 plateau definitions and the contribution of secondary maximality criteria in patients with chronic respiratory disease and healthy controls.

Methods: We retrospectively analyzed 395 CPETs (84 healthy, 135 chronic obstructive pulmonary disease, 99 interstitial lung disease, 77 pulmonary hypertension), comparing consensus-based visual identification of a V˙O2 plateau by three pulmonologists with three commonly used plateau definitions. Additionally, five secondary maximality criteria were evaluated, using strict and liberal thresholds.

Results: The relative V˙O2 plateau definition showed strong agreement with visual assessment (κ = 0.75-0.93), while absolute thresholds were discordant (κ = 0.02-0.31). Overlap between maximality criteria was high in healthy individuals but low in disease groups, suggesting that evaluating multiple criteria in parallel is necessary. However, combining more than 2 secondary criteria in healthy subjects and more than 3 in patients on top of V˙O2 plateau provided minimal additive value.

Conclusion: CPET maximality assessment depends strongly on the criteria applied, potentially altering CPET interpretation and clinical decision-making.